In general, hard butter in a broad sense including cacao butter mostly used for producing chocolate, or fats used for manufacturing margarine/shortening usually exist in several polymorphic forms. Change in crystal form will proceed in hard butter products leading to crystal growth, and causes undesirable phenomena, e.g., so called blooming of the solidified product or graining which is a grainy taste development in cream type products.
Usually, a tempering treatment, a heat treatment to transfer the crystal form of the fat components uniformly, is employed in manufacturing chocolate or margarine/shortening to avoid blooming and/or graining problems. However, since the tempering is a time and energy consuming process and requires precise temperature control, it has been desired to eliminate the tempering process from confectionery manufacturing processes.
There are some fats and oils known in the art that do not need tempering, such as trans-isomerized triglyceride compositions which are high in trans fatty acids (trans fats) and triglyceride compositions high in lauric fatty acid (lauric fats).
However, trans fats are known to develop undesirable flavor due to isomerization which spoils the taste of the resulting chocolate. The lauric fats generate an undesirable "soapy" flavor under some storage conditions. In order to avoid these problems, hard butter compositions that do not need to be tempered, and that do not contain trans fats or lauric fats are desired.
Heretofore, various studies have been made to prevent or control fat blooming of non-transisomerized or non-lauric hard butter compositions. Such studies include improving the hard butter composition through addition of ester-interchanged triglycerides which have long chain and short chain fatty acid residues (U.S. Pat. No. 3,491,677), addition of a surfactant (JP-A-2-249452 and JP-A-3-247240), and addition of an anti-blooming agent comprising B.sub.2 O, wherein B represents behenic acid residue and O represents oleic acid residue (JP-A-62-6635). However, those improved hard butter compositions still require tempering.
Recently, confectionery fat compositions that do not need to be tempered and do not contain trans fats or lauric fats have been proposed. For example, JP-A-61-224934 discloses a hard butter composition containing SSU triglycerides (1,2-saturated-3-unsaturated triglycerides) in the other raw materials for hard butter exhibits good anti-blooming property when molded without tempering treatment. U.S. Pat. No. 5,424,091 discloses a non-tempered fat composition which consists of defined amounts of SSU triglycerides, trisaturated triglycerides, and 1,3-saturated-2-unsaturated triglycerides.
These prior art hard butter compositions have accomplished the improved fat blooming or graining resistance through crystal stabilization by means of a defined amount of SSU and they can provide chocolate or chocolate coating having no blooming problem without tempering. However, since solidified hard butter products, such as solid chocolate, manufactured from those prior art hard butter compositions exhibit poor contraction upon cooling, they stick in the mold and generate problems of workability. Further, SSU type triglycerides are usually made by introducing unsaturated fatty acid, such as oleic acid, selectively in the 1 or 3 position of trisaturated triglyceride through an enzymatic treatment which requires complex procedures and high costs.